In service use, a releasable tubing string connector typically must be able to withstand the effect of substantial tension in the tubing string such as may occur when setting a packer or other well tool. Additionally, the connector must be able to withstand some lesser magnitude of compressive load such as may occur when the tubing strikes or catches upon something as it is lowered into the well. But, the connector also must easily release from the lower section of the tubing string when it is desired to pull the upper section of the string from the well so as to avoid possibly damaging joints in the tubing or the seal between the packer and the well casing.
Prior connectors such as those described in U.S. Pat. Nos. 2,409,811, 3,559,732 and 4,040,649 have utilized various forms of piston and releasable latching arrangements to effect a releasable connection between telescoped tubular members connecting between upper and lower sections of a tubing string. In these prior patented devices, operation of the connectors is pressure dependent, either on the pressure internal to the tubing or the pressure in the annulus between the tubing and the casing above the packer.